Process for lubricating metal working operations

ABSTRACT

A process for lubricating metal working operations involving aluminum, copper and titanium which comprises lubricating such operations with a lubricant comprising a monoester of a dimer of ethylenic monocarboxylic acids having from about 16 to about 22 carbon atoms.

- United States Patent 1191 Aug. 28, 1973 Trites PROCESS FOR LUBRICATING METAL 2.922.763 1/1960 Tierney 252/57 x WORKING OPERATIONS 3,223,635 1/1965 Dwyer 3,492,232 1/1970 Rosenberg 252/57 X [75] Inventor: Robert T. Trites, Cincinnati, Ohio [73] Assignee: Emery Industries, lnc., Cincinnati, Primary Examiner--Daniel E. Wyman o Assistant Examiner-W. Cannon [22] Filed. June 16 1969 Attorney-Ronald F. Weiszmann and John D. Rice 1 [21] Appl. No.: 834,240

[ ABSTRACT 52 U.S. c1. 252/56 R, 260/407 A Pmess lubricating meta perafins [511 lm. c1 Cl0m 1/26 aluminum and titanium which [58] Fi f Search 252/56, 260/407 prises lubricating such operations with a lubricant comprising a monoester of a dimer of ethylenic monocar- [56] References Cited boxylic acids having from about 16 to about 22 carbon UNITED STATES PATENTS 10/1956 Gottshall et al. 252/57 atoms.

3 Claims, No Drawings PROCESS FOR LUBRICATING METAL WORKING OPERATIONS BACKGROUND OF THE INVENTION The field of this invention relates to metal working operations and particularly to metal working operations involving aluminum, copper, titanium and alloys of these metals.

Metal working operations, for example, forging, hot pressing, blanking, bending, stamping, drawing, cutting, punching, spinning and the like, generally employ a lubricant to facilitate the metal working operation. Lubricants greatly improve metal working operations in that they can reduce the power required for the operation, prevent sticking and decrease wear of dies and cutting bits. Common lubricants in metal working operations have been vegetable oilsQanimal oils and mineral oils, for example, palm oil, tallow oils and petroleum oils.

Metal working operations generally expose unprotected metal surfaces to the atmosphere and other corrosive influences which can result in the formation of non-adherent oxides and hydroxides of the metal. Therefore, corrosion inhibitors are often added to metal working lubricants. v

In metal working operations involving aluminum, copper, titanium and alloys of these metal's it is especially desirable to protect the metal worked from corrosion, i.e., the formation of non-adherent oxides and hydroxides. In particular, aluminum is prone to form a white non-adherent hydroxide if it is not protected during metal working operations.

It is known in the art that dimers of ethylenic monocarboxylic acids having from about 16 to about 22 carbon atoms may be used as lubricants for metal working operations. For example, U.S. Pat. No. 3,006,849 assigned to the Standard Oil Company discloses a metal working process for ferrous metals involving a lubricant composition employing such polymerized fatty acids. In addition, US. Pat. No. 2,922,763 assigned to Texaco, Inc. discloses'the use of full esters of such polymerized fatty acids in high temperature lubricant compositions.

However, neither dibasic dimer acids nor the full esters of such acids is completely satisfactory in metal working operations involving aluminum, copper and titanium. While the dibasic acid dimers are excellent lubricants and provide corrosion resistance to these metals, these particular metals tend to form insoluble soaps with dimer acids which are inactive sludges. In addition, the dimer acids tend to stain aluminum in metal working operations so that it does not present a pleasant aesthetic appearance. Similarly, the full esters of the dibasic acid esters are not completely satisfactory lubricants in that the full esters do not render aluminum, copper and titanium corrosion resistant.

SUMMARY OF THE INVENTION This invention presents a novel process for lubricating metal working operations involving aluminum, copper, titanium and alloys of these metals which comprises lubricating such operations with a monoester of a dimer acid of ethylenic monocarboxylic acids having from 16 to 22 carbon atoms. The advantages of the process of this invention are derived from the 'unique properties of the dimer acid ester utilized herein. These 2 dimer acid esters surprisingly do not form sludges, or stain the metal being worked and yet surprisingly are excellent lubricants and corrosion inhibitors.

DISCUSSION OF THE INVENTION AND ITS PREFERRED EMBODIMENTS This invention relates to a process for lubricating metal working operations involving aluminum, copper, titanium and alloys of these metals which comprises lubricating such operations with a "surprisingly useful lubricant comprising monoesters of dimers of ethylenic monocarboxylic acids having from about 16 to about 22 carbon atoms.

Typical of the metal working operations included within the scope of this invention are forging, hot pressing, blanking, bending, stamping, drawing, cutting, punching, spinning, and the like. These operations are well .known in the metal working art. A fuller (ICSCI'IP', tion of these operations all of which are common to the metal working art, can be found in the book titled AluminumForming published by the ReynoldsMetals Company, Richmond, Virginia.

For the unique lubricant of the process of this invention to be most effective, the temperature of the metal involved in the operation should not exceed about 800 F, and preferably should not exceed about 600 F;

The surprisingly useful lubricants utilized in the process of this'invention comprise the methyl, ethyl and propyl monoesters of dimers of ethylenic monocarboxylic acids having from about l6 toabout 22 carbon atoms. Such esters are known in the prior art.

The dimer acids from which the monoesters of this invention are prepared are wellknown in the prior art. More specifically, it is well known that unsaturated fatty acids having from about "l 6 to about 22 carbon atoms may be polymerized to yield'dimeric forms of the monomeric acids. The resulting dimers are dibasic carboxylic acids containing from about 32 to about 44 carbon atoms. For example, oleicacid, recinoleic acid, linoleic acid, lineolaidic acid and eleostearic acid can be polymerized to form dimer acids which are dibasic carboxylic acids. An especially preferred dibasic dimer acid for use in forming the esters of this invention contains about 36 carbon atoms and is formed by the polymerization of two ethylenic monobasic acids containing about 18 carbon atoms, as for example oleic acid.

Processes for polymerizing ethylenic monobasic fatty acids are well known in the prior art. By way of illustration, reference may be had to the followingpatents for further description of the polymeric acids, and methods for their preparation: US. Pat. Nos. 2,793,219 and 2,955,l2l assigned to Emery Industries, Inc. Briefly, the methods entail heating the unsaturated fatty acids in a steam pressure vessel at temperatures of from about I C to about 360 C for about3 to about 10 hours to produce a product consisting mainly of dimer acids. I

An especiallyuseful, commercially available dimeric carboxylic acid for forming the monoesters highly preferred in this invention is avilable from Emery Industries, Inc. under the trade name Empol I010. Empol 1010 is a dibasic acid having about 36 carbon atoms produced by the polymerization at midmolecule of two unsaturated mono-basic fatty acids containing about l8 carbon atoms. Typical specifications for the commercial product are as follows:

Color (1: transmission 440/550 mmu) 82/99 3 Iodine value (mg. lJgm.) 20 Neutralization equivalent (mgKOH/gm.) 287 Acid value (mgKOH/gm.) 196 Flash point ("F) 585 The monoesters useful in this invention are the methyl, ethyl and propyl esters of dimers of ethylenic monocarboxylic acids having from about 16 to about 22 carbon atoms. Such monoesters are most conveniently formed by heating the above mentioned dibasic dimer acids to a temperature of from about 180 C to about 260 C, and adding the appropriate alcohol, viz., methanol, ethanol or propanol, continuously, slowly and sub-surface to the hot dimer acid until the dimer acid has been reacted to one-half its theoretical acid value. The resulting esterifiedproduct is a mixture comprising primarily monoester dimerate, and some diester dimerate and unreacted dimer acid. The methyl ester is the preferred monoester in the process of this invention.

In practical applications it is not generally feasible to separate the components of the above mentioned esterified compositions because of the economic costs involved. It has been surprisingly found, however, that it is not necessary to separate the components of the esterification product in order to derive substantially the benefits achieved with the monoester dimerate uncontaminated with unreacted dimer acid and diester dimcrate. It is not clear why this is the case, but it is theorized that the monoester dimerate solubilizes the metallic soap sludges which dimer acids form with aluminum, copper, and titanium in metalworking operations with the result that staining is substantially prevented and the dimer acid remains in an active form. In such compositions the monoester dimerate should comprise at least 25 percent by weight of the mixture of dimers and preferably at least 50 percent by weight of the mixture to be optimumly effective.

While the monoester dimerates of this invention can be used per se in metal working operations, it is most practical to dilute the monoester dimerates with inexpensive mineral oil carriers. Suitable mineral oil carriers for the monoester dimerates are light mineral oils having a viscosity of from about 100 to about 1,000 Saybolt seconds Universal at 100 F. Generally the monoester lubricant should comprise from about 5 to 20 percent by weight, preferably from about to percent by weight of the mineral oil carrier. Other suitable carriers, as for example, soy bean oil, can be employed.

The lubricant compositions of this invention can be applied to the metal to be worked prior to the metal working operation in any suitable manner which insures thorough contact of the surface of the metal. For example, the lubricant can be brushed or sprayed on the metal, or the metal can be immersed in a bath of the lubricant. In high speed metal forming operations the lubricant is preferably sprayed on the metal to be worked, or the metal is immersed in a bath of the lubricant. When these latter methods of application are employed in metal working operations involving aluminum, copper and titanium, dibasic dimer acid lubricants are especially prone to form metallic soap sludges because of continued exposure to these metals. The monoester dimerates of this invention are especially preferred when these methods of lubricant application are employed.

In accordance with this invention, the monoester dimerate lubricant isfirst applied to the metal to be worked, and then the metal is subjected to one or more metal working operations, as for example, the metal working operations hereinbefore discussed. When the metal working operation is completed, it is often desirable to remove the lubricant coating the metal in a degreasing operation. Any suitable degreasing operation can be employed, but is preferred to remove the lubricant with a high velocity mist of trichloroethylene.

It is a surprising feature of this invention that even after the lubricant compositions empolyed in the process of this invention are. removed from the metal, i.e., aluminum, copper, or titanium, the corrosion resistance of these metals is greatly increased. It should be understood that this is a passivating effect which leaves the surface of these metals substantially colorless and unchanged.

The metal working process of this invention is especially advantageous for working aluminum in that staining of aluminum due to lubricants used in metal working operations is a severe problem. It has been found that this problem is substantially eliminated by employing the lubricant compositions of this invention in metal working operations involving aluminum.

Among the alloys included within the scope of this invention are alloys of aluminum, copper, and titanium with copper, manganese, zinc, magnesium, and silicon, for example brass, bronze, and duraluminum.

The following examples are given to illustrate several preferred embodiments of the process for lubricating metal working operations involving aluminum, copper and titanium disclosed herein. These examples are not intended to be a limitation upon the invention. Unless stated to the contrary all percentages and ratios are on a weight basis.

EXAMPLE I A lubricant composition is formed comprising per cent by weight of a light petroleum oil having a viscosity of Saybolt seconds Universal at 100 F and 10 percent by weight of the methyl monoester of a dimer of oleic acid. This composition is continuously sprayed on to aluminum blanks having a thickness of 0.064 inches. The excess non-adherent lubricant is collected and recirculated for subsequent applications.

The lubricated aluminum blanks are placed on a 100 ton drawing and forming press and in four draws are formed in to small deeply drawed cylindrical cups 20 inches high with a diameter of 10 inches.

The resulting cup which is formed is corrosion resistant, and there is no staining due to the lubricant employed in the process.

The 'recirulated lubricant composition shows no sludge formation.

EXAMPLE n A lubricant composition comprising a mixture of methyl monoester of a dimer'acid and diester dimerate and unreacted dimer acid is formed in the following manner:

The dimer of oleic acid is heated to 210 C and methanol is added to the heated dimer acid slowly, continuously and subsurface until the dimer acid has been reacted to one-half its theoretical acid value. The resulting composition is a mixture comprised of the methyl monoester of the dimer acid, the dimethyl ester of the EXAMPLE lIl When the lubricant composition of Example II is employed in stamping copper blanks to form trays substantially the same results are obtained in that there is no staining due to the lubricant, and the copper is rendered corrosion resistant.

EXAMPLE IV When the lubricant composition of Example ll is employed in stamping titanium blanks substantially the same results are obtained in that there is no staining due to the lubricant, and the titanium is rendered corrosion resistant.

What is claimed is: l. A lubricant composition suitable for use in processing aluminum, copper and titanium metals and alloys comprising a. from about to percent by weight of a mineral oil carrier fluid having an SSU viscosity of about to 1,000 at 100 F and b. from about 5 to 20 percent by weight, based on the mineral oil of the monoester reaction product of about 1 mole of dimer acid containing from about 32 to 44 carbon atoms and about 1 mole of a lower alkyl alcohol selected from the group consisting of methanol, ethanol and propanol.

2. The composition of claim 1 wherein the dimer acid contains about 36 carbon atoms.

3. A composition as in claim 2 wherein the monoester reaction product comprises from about 10 to 15 percent by weight of the mineral oil. 

2. The compOsition of claim 1 wherein the dimer acid contains about 36 carbon atoms.
 3. A composition as in claim 2 wherein the monoester reaction product comprises from about 10 to 15 percent by weight of the mineral oil. 